burn slots in squish area ?

[big block fiero]

Originally Posted by Calypso

Do I read this correct that you have found that radiusing the squish pad edges and using groove together has proven beneficial on your dyno?

Not radiusing the squish pad edges and using a groove together has shown positive results. Our focus over the last 5 months was been racing and not development . I know that proper A,B,A testing would help our racing program but we often make more then one change which spoils the test. I,m not the one making these poor decisions and I'm told that we don't have time for testing now but will find time to do this testing my way later. I have been putting various technologies in our engines without A,B,A testing and have always seen hp improvements. We have never yet lost power with any of my changes so wildman SR has gotten comfortable with the idea that this is easier then it really is. When the opportunity arises I will do the proper testing and report on the results. I have a situation that may very soon give me the ability to test every idea and concept anyday and everyday so it could get real interesting.

[seattle smitty]

I feel a case of dyno-envy coming on . . . way to go!!!

[GMH326ci]

all the photos shown have large squish area? will the groove work on smaller squish areas? the heads i use i asume are fairly effecient as they dont require alot of timing say 28deg

[automotivebreath]

Here's pictures of one of the groove layouts I have been toying
with lately. I have a couple of engines running with these, this
is my first look after run time.

[crazyman]

Looks like melted aluminum specks. Did it sound like it spark knocked?

In theory, you are blowing the heat from the exhaust valve into the vapor. I wonder how it would've looked blowing the vapor towards the exhaust valve.

[Jesse Lackman]

I did back to back grooves testing on my dyno.

Enigne Dyno Grooves Testing

For what it's worth this guy took the before and after grooves sound files and analyzed them;

The Groovy Sounds of a 360 Magnum Engine

I made a large mistake by not nailing down BSFC with steady state tests - I will do that next time. Also I'm planning on recording engine noise with a contact microphone setup and maybe a knock sensor to see if the grooves actually cut down on detonation. I'm very slow though so it might not happen for a while.

For the first time I understand how grooves aimed at the exhaust valve might help inhibit reversion. Did that car have a full exhaust? It's not too hard to build engines that will not have reversion at WOT anyway, when the VE goes over 100% some of that VE can be airflow that is not "trapped" and is blowing right through the engine thus there could be little or no WOT reversion.

So using grooves to limit reversion at idle or low RPM/low throttle would limit their effectiveness at doing anything good at WOT right?

(Thinking) - if there is no reversion at WOT why waste the groove for reversion control?

I'm wondering if for detonation control groove(s) should be aimed at the outside of the intake valve where the intake valve meets the cylinder wall as this seems to be where detonation starts.

[automotivebreath]

Originally Posted by Jesse Lackman

For the first time I understand how grooves aimed at the exhaust valve might
help inhibit reversion.

Did that car have a full exhaust?

So using grooves to limit reversion at idle or low RPM/low throttle would limit
their effectiveness at doing anything good at WOT right?

(Thinking) - if there is no reversion at WOT why waste the groove for reversion
control?
.

How would the grooves aimed at the exhaust valve help with reversion?

This car runs open headers, 11:1 compression premium Exxon gas. The reason
I tried the grooves pointing towards the exhaust was to direct squish action
in the hot area where the flame develops, aganst the grain of swirl generated
in cylinder flow. I didn't consider reversion.

Originally Posted by crazyman

Looks like melted aluminum specks. Did it sound like it spark knocked?

I'm thinking the roughness on the piston is from high humidity. The engine didn't
show signs of detonation, I'll check the piston tops for damage. The plugs
were running snow white with a slightly rich Air/fuel ratio, no signs of speckles.

[tommurphy73]

Hi,

I put burn slots in the squish area of my first cylinder head recently. Unfortunately I have no photos of the work as my camera was not working. Basically the engine spec remained the same except for this work. I put one slot on the squish pad at the opposite side of the chamber from the spark plug pointing at the spark plug and I put one behind the spark plug which was tangential to the edge of the spark plug. I have no before and after dyno results but the feedback from the driver is that the idle is much smoother and the ability of the engine to pull from low revs is much improved. A dead spot most likely caused by bad carburettor setup has virtually disappeared. The high rpm performance does not appear to have changed at all. I am very pleased with the results and am contemplating doing it on future builds. Unfortunately this is more anecdotal evidence with no real numbers to back it but all I have for the moment.

Best Regards
Tom

[automotivebreath]

Hi Tom,
Thanks for the information. Can you provide details of the engine
and application?

[tommurphy73]

Hi,

The engine is Ford Pinto 2.0l sohc engine that is fitted to a Ford Escort Mark2 road rally car. The spec of the engine is not massive. It is running 10.5:1 static compression ratio, 285 degree cam, twin side draft weber 48 carburettors. The head has bathtub chamber with the spark plug pointing towards the inlet valve and in the direct path of the incoming charge. The following is a photo of it in the early stages of home porting.



Regards
Tom